Shale reservoir development has gradually become the focus of global energy attention, horizontal well large-scale volume fracturing technology has become an economic and effective means of shale reservoir development. After large-scale fracturing of shale reservoir, fracturing fluid will produce strong imbibition effect in the reservoir. However, the mechanism of how the remaining fracturing fluid affects the shale formation is unclear. In this paper, the core of some blocks in different areas is selected for the main shale reservoirs in China, and the basic physical characteristics of rock samples in different areas are tested. On this basis, the forced imbibition law of different types of shale oil was studied, and the differences of forced imbibition characteristics and micro-production law of crude oil were clarified with nuclear magnetic resonance technology. The results show that: Under the corresponding imbibition conditions, the imbibition characteristics of fracturing fluid in different regions are quite different. The pressure at the injection end of the core attracted by forced imbibition in Qinghai area decreases the most. It can be seen that oil-water displacement occurs during the imbibition process of fracturing fluid, and the oil phase content in the rock sample decreases. The imbibition effect is more obvious in Qinghai and Gulong areas, and the oil phase content in rock samples attracted by fracturing fluid has a greater change. This study provides theoretical and technical support for the imbibition effect of fracturing fluid and the distribution of crude oil in shale oil wells after large-scale fracturing.